Noncurling fabric



Patented Apr. 21, 1953 Heinz ,Ginzel, Dornbirn, Vorarlberg, Austria No Drawing. Application July 11, 1947, Serial No. 760,512. In Germany November 19, 1942 Section 1, Public Law 690, August s, 1946 Patent expires November 19, 1962 9 Claims.

This invention relates to non-curling, chemically stiffened fabrics, the textiles produced therefrom anda method of producing such fabrics and textiles.

Chemically 'stifiehed fabrics, made of native or regenerated cellulose, particularly those highly improved and stiffened by a treatment with concentrated mineral acids, as sulphuric acid, or with other hydrolysing and/or swelling agents, as zinc chloride, calcium thiocyanate, ammoniacal copper oxide or with mercerising lye at low temperatures, often have thedisagreeable quality of curling when dried or ironed. Such a tendency to curl exists with fabrics chemically stiffened on the whole surface or a large part of their surface, especially cases where the stiffened portions form a connected ground. It has been recommended that the curling tendency may be avoided by passing the parchmentized material through successive jaws of a calender having at least two jaws.

A permanent suspension of the curling tendency of parchmentized fabrics could however not be obtained by this process. According. to a later proposal for obtaining non-curling parchmentized or otherwise chemically permanently stiffened fabrics, fabrics the warp or weft of which orboth woven by means of normally right-hand and lefthand twisted yarns interspersed therein, for example, alternating individually or in groups, that is to say yarns twisted alternating in different directions are subjected to parchmentizing or an equivalent stiffening process. This latter process needs special measures in spinning and weaving because the working up of yarns twisted in different directions makes it necessary to dye the different yarns with different colors, which colors have tobe removed after weaving andalso the production of the fabrics requires special precautions.

An object of this invention isto provide chemically stiffened cellulose containing fine fabrics, and more particularly an organdie, permanently free from a curling tendency. Another object of this invention is to provide a simple method which makes it possible to produce parchmentized fine fabricsflwhich are free from inner tensions without being passed through successive jaws of a calender and which keep permanently a noncurling character. Other objects of this invention will appear as the description proceeds.

According to this invention chemically stiffened cellulose containing fine fabrics consist of threads .(yarns or twlnes) twisted in one direction only,

having an English yarn number over 60, and more particularly at least 80, the warp and the weft being substantially equal in weight.

The invention is based on the new recognition that the curling tendency of chemically improved, stiffened fabrics is a function of the distribution of the weights of warp and weft. While 2 parchmentized fabrics, made of the usual fine fabrics, show a well known very large curling tendency, the coarser fabrics. which are treated with concentrated sulphuric acid to provide an imitation linen, do not show this tendency. It was first suggested that the curling tendency in the coarse fabrics had been suspended by the strength of the threads, but this has been proved to be wrong. Further investigations have shown that the absence of the curling tendency of the coarse fabrics is a result of theirstructure. Such comparatively coarse fabrics usually have a square or nearly square structure, as these fabrics contain approximately the same number of yarns in one unit of length of weft and warp, and the yarns of weft and warp have the same, strength, measured by the yarn number. Such coarse fabrics are for instance fabrics with a set of 21/ 21 and an English yarn number of 30/30, or a set of 16/16 and .an English yarn number of 20/20. The set is the number of threads or yarns in the warp and weft in 3 1 Paris inch (6.767 mm.), and the English number indicates how many hanks of 840 yards (768.10 In.) weigh one pound (453.59 g.), so that a higher number indicates to a finer yarn. In contradistinction to the structure of such coarse fabrics used for the imitation of linen, there are used for the production of chemically stiffened transparent fine fabrics mainly raw fabrics with a set of 24/21 and an English yarn number of /120. With the usual fine fabrics, used for parchmentizing, the set, i. e. the number of threads in the warp on the one hand and in the weft on the other hand is more unequal than with the coarse fabrics, but, more importantly, the strength of the yarns measured by their yarn numbers is very different in'weft and warp. Experiments have now shown thatfine fabrics with a yarn number of more than 60, particularly 80 and more, for instance 100, 130, etc., do not curl after parchmentizing or other chemical stiffening, if the original fabrics were set approximately square, that is with the same number of threads and the same yarn numbers in weft and warp. The reason is, as was proved, the approxi mate equality of weight of weft and warp in a unit of area (for instance one m?) with such square set fabrics. It may be seen that the expressions 22 I Nw and 1 in N f wherein E is the number of threads per unit of area (for example, in a square meter), N is the English yarn number, a w and f designate warp and weft, respectively, represent values which are proportional to the weight of the warp and the weft, respectively, in the unit :of area, since the English-yarn number is inverselyproportional to the weight of thread per unit of length. Approximate equality between these expressions will, ac-

cordingly, indicate the presence of the conditions necessary to avoid curling of the parchmentized fine fabric.

In accordance with this finding that the crucial point is the equilibrium of weight between weft and warp, it was concluded that unsquare set fine fabrics also should be free ofea curlingtendency after parchmentizing if the fabric :contains approximately the same weight of weft and warp in one unit of area, for instance a smallernuniber of stronger weft threads and a larger number of weaker warp threads. This :has indeed been proved .by experiments. A .small deviation .from the equilibrium of Weightedoesnot.largely influence .the success. Generally ;-a -.difierence up .to .10. 92,, more particularly a difference pf not-more than about 7%, between the weights of wetter warp "and half of .the weight of QtheiabricZisaHQW able without causing a considerable tendency towards curling. The nearer -the weights .of weft andwarp cometdhalf of the weight of theiabric,

'thejmore'the tendency to curl is,prevented.

It has also been found that the manner of chemical treatment, especially the degree of shrinkage resulting from parchmentizing-iorother chemical sti'fiening is without essential importance, because ,due to the shrinking of stronger yarns in'the warp, the number of .unflirunk yarns inthe'weft will rise proportionally, anjd vice .versa, :solthat the shrinking will result'in :an;increase1n weight of one unit .ojharea of the jfabri lhui; the .;relation of "the weights of warp 'and weft will remain ,nearly constant. As ,well, the relation beftweenithe weights of warp .and weftremains-constant in the ,case o'fshrinking .in bdthdirec'tions.

The fabrics produced iin-accordance with this inventiontmay he stiffened :byany .chemical proc- Jess producing a permanent stifiening efiect i-such -.as parchmentizing or vtransparentizing :with mineral acids, particularly with highly concernz-trated sulphuric .acid or .other parchmentizing agents, as ammoniacal copper oxide solution, :zinc .chloride, :calcium thiocyanate .and so on, or .by treatment withmercerisingllyesat:1ow temperatures, the -.concentration, temperature :and :time of :such treatments :being adjusted in i8 wa-y .eknown, corresponding to the ;material .to be treated. The :stifiening may lice carried 10111; :in combination with ss'hrinking :or :stre'tching "the 4 surfaces in the iorm of a pattern, or by other eguallytwellrknown methods.

'Breierab1y,ifineztextilesoicetton.orlregenerated cellulose, as artificial silk or rayon (viscose-,

' :tcopper cellulose or acetate silk or wool) are employed in the practice of this invention. The 'la-brics-may contain fancy threads of the same or -:other :materials, or instance animal fibres or synthetic fibres, as polyamide fibres, glass fibres,

:1 .metal'fibres, metalized fibres, and so on. The

fabrics also may-contain corrosible threads or ,yarns, .whichimay be removed before, during, or vaiter thebhemical stiffening process by one of the known wet or dry etching processes. The

" fabrics consist of uni-directionally twisted threads, i. e., they consist of either right-hand or of left-hand .twisted ,threads. Standard. twisted iyarns aswellxasicrepe,yarnsimaybe nseii.

Theinvention oftersatheadvantage.otproyidlng non-curling, chemically stifiened, preferably xparchmentized .fineiabrics, which .may he 31130 :duced without using complicated .measures, as theuseioi yarns-twisted inldifierentdirectionszand also without .rspecial weaving equipment. An-

:other iadvantage 218 :that the tensile strength and the resistance :against rubbing are nearly -.;e ual in :both-zdirections (weftand .warp) with iarjfinal product:ofssguareistructure. .These-,qualities;also 'prevailwith textiles produced or such 'fabrics, as

decorative -.clothes, trimmed products, :co'llars,

40 ibleachediand :thenparchmentized withssulphuric acid of 1'54 LB. :for :8 sseconds atv a vtemperature ,o'f

0 C. "The ;f.ollowing fabrics were used:

ATABLEA Original fabrics a. b c d .e ,f g f h c 2622 15:3 41:5 26125 212.11 1216 11 4.7- :s are 1 19.2 E see 4.4 721.70 18.;4 39.4 "6:? T175510 11540 34. 8 :0 14.18 14.13 sec, :0

TABLE B Fabrics,uitenthiemhemicaltstifleniny 11 3b c 11 f *f .g i? n a;

res: 1316': 14Z- 2 1 3190 2Z0 :21.-5; 19.1- some 4.4 ,Do. 21.4 18.181 20.10 6.7 Do. 21.:4 21:4: "a21.=4 :0 2130. .-I8.;1'.18E1;W. 5 18.10 10 Do.

.The invention may be applied to fabrics .stiffened on the whole of their surfaces .or stiffened .locally only on parts of the surfaces, the latter being effected.byprintingstifiening agents on the .In the preceding tables:

Column 51;, indicates the seriesmumber 1'0 the iexperiment; column l the breath cftthe fabric;

column 0, 'set (number :of threads in .174Paris inch); column it, English number of yarn itthe first ..number in .columns 0 and drefers itothe warp and lthesecond 'to the weft); column "e,

weight o'fonem; of warping; columnj, weight of one m? of weft in g; column g, total weight of one squaremeter; column h, half of the weight of one squaremeter of the fabric; and column 1, difference in weight of warp or weft from value it in percent.

These tables prove, that the fine fabrics, generally used for chemical stiffening (Examples 1 of the tables) show a very large deviation of weight of the weft of the warp amounting to 26 or 27% in both directions from the equilibrium of weight (half of the total weight of the fabric). Such fabrics roll strongly after stiffening.

In contrast thereto the fabrics according to the Examples 2 to 6 do not have any tendency towards curling. Those fabrics have approximately the same weights of weft and warp, the deviation from the equilibrium of weight in the Examples 2, 3 and 4 being only 2.0%, 4.4% and 6.7% respectively, while fabrics according to the Examples 5 and 6 are completely in equilibrium as to the weights of warp and weft.

The Examples 2 to 4 demonstrate an embodiment of the invention with the use of approximately square set fabrics (fabrics with about the same number of threads and equal strength of threads in Weft and warp). The Examples 5 and 6 show an embodiment of the invention with the use of unsquare set original fabrics, the final products showing an approximatelysquare set. The comparison of the examples proves that the crucial point in removing the tendency to curl is the maintenance of the substantial equality of weight between weft and warp. The Examples 1a, 1b, 2a, 21) (Table B) prove further, that the degree of shrinkage produced by the finishing has no decisive influence on the curling tendency.

I claim:

1. An organdie consisting of parchmentized threads twisted in one direction only, said threads having an English yarn number over 60, the weight of the warp and the weight of the weft of the organdie in a unit of area each being within 10% of one-half of the total weight of the said unit of area.

2. An organdie consisting of parchmentized threads twisted in one direction only, said threads having an English. yarn number of at least 80, the weight of the warp and the weight of the weft of the organdie in a unit of area each being within 10% of one-half of the total Weight of the said unit of area.

3. An organdie consisting of parchmentized threads twisted in one direction only, said threads having an English yarn number over 60, and the weight of the warp and the weight of the weft and N f differ by less than 10% from one another, Ew being the number of warp threads in a unit of area, Ef being the number of weft threads in the same unit of area, and Nw and Ni being,

respectively, the English yarn number of the.

warp threads and the weft threads.

6. An organdie as claimed in claim 1 in which the threads are parchmentized at said defined areas and not parchmentized at other defined areas.

7. An organdie as claimed in claim 2 in which 7 the threads are parchmentized at said defined areas and not parchmentized at other defined areas.

8. An organdie consisting of parchmentized threads twisted in one direction only, said threads having an English yarn number of about 80, the weight of the warp and the weight of the weft of the organdie in a unit of area each being within 7% of one-half of the total weight of the said unit of area.

9. An organdie as claimed in claim 8 in which the threads are parchmentized at certain defined areas and not parchmentized at other defined areas.

HEINZ GINZEL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,215,938 Schonholzer Sept. 24, 1940 2,249,039 Platt July 15, 1941 2,400,182 Whitman May 14, 1946 OTHER REFERENCES Staple Cotton Fabric, Hoye, published 1942, McGrawHill Book Co., New York, pages 57, 58 and 60. 

